1. Field of the Invention
The present invention relates to a method and an apparatus for the quantitative determination of surface properties.
The nature of surfaces is an important property of day-to-day objects, such as motor vehicles and other useful objects for example, and determines to a large extent the overall impression given to the human observer. One example includes the high-gloss or metallic coatings on vehicle bodies.
In the context of the invention, surface properties are understood to mean in particular those physical properties of a surface which determine how a surface looks to a human observer. In particular, these include properties such as macrostructure and microstructure, topography, colour, colour point, brightness of the colour, gloss, image sharpness, haze, surface texture, roughness and “orange peel” effect or coarseness.
In order to reproducibly evaluate the quality of surfaces, particularly of these high-gloss coatings, measuring devices are required which detect specifically those physical parameters that determine to a significant extent the overall impression given to a human observer.
2. Description of Related Art
Recently, so-called effect pigment coatings have been gaining increasing popularity. These coatings contain effect pigments which reflect in different ways the light irradiated onto them. From the prior art, apparatuses and methods are known for quantitatively assessing even such effect pigment coatings.
In one known method, for example, a given threshold value for an intensity of the reflected light is defined, and only those surface regions of an observed surface which have an intensity above this threshold value are taken into account. The measurement result is integrated across the respective intensities of the individual surface segments taken into account. This evaluation provides a clue about the optical properties of the surface analysed. However, it has been found that even surfaces which have identical or similar result values from this evaluation can act in very different ways when looked at directly by the human eye.
The object of the present invention is therefore to allow a more accurate classification of surfaces to be analysed.